There are a number of fluid transfer applications (e.g., applications in which fluid is being administered to and/or drawn from a patient) that require a medical practitioner to take a sample of the blood being drawn from the patient and/or the fluid being transferred to the patient. In such applications, the medical practitioner may utilize a fluid transfer set (e.g., a tubing set) that includes monitoring lines that are, in turn, connected (e.g., at the downstream end) to a catheter placed in the patient's artery or vein. A fluid source (e.g. saline bag) is typically connected to the upstream end of the monitoring line so that the monitoring line may be flushed via a saline drip.
The fluid transfer set may also include a sample port that that is in fluid communication with (and creates fluid communication between) the downstream and upstream ends of the monitoring line. The sample port allows the medical practitioner to draw a sample of the blood or fluid without removing the catheter from the patient or otherwise disconnecting the components of the fluid transfer set. However, when sampling a fluid (e.g. blood) from a conventional T-shaped sampling port, the downstream and upstream openings to the sampling port (e.g., a chamber of the port) are left unrestricted to fluid flow. Therefore, blood may be drawn from the upstream portion of the monitoring line where the blood may have been sitting in the system for some time and/or diluted with saline. Such a blood sample may produce erroneous results and is, therefore, not preferred for lab analysis. To avoid taking a diluted blood/fluid sample, some prior art systems use stopcocks to close off upstream fluid communication during sampling. However, stopcocks add cost and often require substantial manipulation from the medical practitioner during use.
Furthermore, in some critical care applications, the medical practitioner may be required to regularly monitor the patient's arterial or venous blood pressure. In such applications, the fluid transfer set may also include a pressure transducer (located upstream from the sampling port) that connects to a display that graphically shows a read-out of the arterial or venous blood pressure. To avoid negative interference with the pressure measurement that may be caused by certain components within the sampling port (e.g. resilient silicone septum), some prior art systems use stopcocks to close off fluid communication to portions of the sampling port during pressure measurement. However, as mentioned previously, stopcocks add cost and often require substantial manipulation from the medical practitioner during use.